问题补充:
So many natural disasters are believedover the recent years because of the frequent unreasonable mankind activities.
A. to have come about
B. to come about
C. coming about
D. to be coming about
答案:
(答案→)A. to have come about
B. to come about
C. coming about
D. to be coming about
解析:可联系答.案.网客服索取。